The number of properties listed for sale in Aspen, Snowmass Village and Basalt has dropped 11 percent since last year, indicating a strengthening market, according to a monthly report put out by local real estate broker Andrew Ernemann.

Aspen listings overall have dropped by 12 percent since last year, while the number of condominiums and single-family homes for sale are down by 15 and 10 percent, respectively.

Driving the trend is the reduction in the number of vacant land parcels listed in Aspen. Those properties are down by about 16 percent from last year. That’s because there are fewer of them available; over the past year most of the real estate activity in Aspen has been vacant land sales, Ernemann said.

“That segment of the market has really helped drive the Aspen market,” Ernemann said, adding that land sales have improved consumer confidence in real estate here.

With fewer properties listed for sale, prices will start to rise again. That already is happening in places like the West End and Red Mountain, he said.

“I think in Aspen you’re seeing increases in sales activity year over year and a decrease in inventory,” Ernemann said. “The two go hand in hand. Normally, when you see inventory dropping and sales increasing that puts upward pressures on pricing and I think we’re seeing that already happen in some places.”

The story is slightly different in Snowmass Village where the number of listings is down by about 5 percent. In Snowmass, single-family homes for sale are down by about 20 percent, vacant land parcels are up slightly and condominium inventory remains flat. That’s likely because 122 new residences at the Viceroy Snowmass resort hotel went on the market in the past year. Still, they have been selling, which is a good sign, Ernemann said.

Of the three municipalities, Basalt has seen the largest drop — 24 percent — in inventory since last year. That’s because there are fewer single-family homes and condominiums on the market, he said.

Overall, January and February dollar volumes are lower than last year. Last year, a surge in sales didn’t happen until the end of 2012, Ernemann noted. Generally, the number of properties that have closed or are under contract this year is on pace with 2012 activity, he said.

The drop in inventory will eventually transform into a seller’s market, which hasn’t happened since the great recession hit in 2008, he said.

“It’s a good thing certainly for sellers who have been hung out to dry for a couple of years,” Ernemann said.

The drop in available inventory is a good omen, said John Sarpa, the real estate representative on the board of the Aspen Chamber Resort Association, at a recent board meeting. It means that the local economy is improving and that could positively impact local businesses, he said.

“It’s really turning out to be what looks like a strong summer,” Sarpa said.